QSimplex: API cleanup [2/3]: disable copying

QSimplex is not designed to be copied, so disable explicitly.

Change-Id: Ia1ddcfe905380e594930717c7c55bb38a7dd4059
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
QSimplex: API cleanup [3/3]: add inline keyword

The functions valueAt() and setValueAdd() were defined inline out-of-body,
but not declared inline. Fix by adding inline to the declarations, too.

This has in the past caused warnings on exported classes on MinGW, and it's
simply wrong, too.

Change-Id: I5922cb9ca0c5ee37408f553f0aad0e3264853827
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
QSimplex: make non-polymorphic

This class is never inherited from, so save the vtable, and
everything that goes with it (typeinfo, ...).

Effects on Linux AMD64 GCC 4.9-trunk release stripped:
  text:   -248B
  data:    -64B
  relocs:   -5

Change-Id: I12eec1115529eb3fc873fb9a9aacc150d9937fb9
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>